There is a need to be able to readily detect, separate and quantify trace amounts of sulfur mustard agents and their decomposition by-products in aqueous solution in combat situations for detecting agent use as well as in the laboratory for analyzing intelligence samples. The decomposition by-products are more likely to be encountered in the environment rather than the agent alone. This need is also present in environmental studies and generally in analytical methodology for the identification of alkyl sulfides in an aqueous matrix.
Sulfur mustards are currently analyzed by colorimetry using 4-(p-nitrobenzyl)pyridine (DB-3) (Holzman, G. Jr. Swift, E. H. and Niemann, C. OSRD 4288, The Colorimetric Estimation of NH-3 and DB-3, 27 Oct. 1944; Esptein, J. Rosenthal, R. W. and Ess, R. J. Uses of 4-(p-Nitrobenzyl)pyridine As Analytical Reagent for Ethyleneimines and Alkylating Agents, Anal. Chem. 27, 1435-9 (1955). This is a general test which gives positive results for practically all alkylating agents and false positives for some acylating agents. However, this test is not effective for the decomposition by-products of sulfur mustards.
Gas chromatography (GC) has also been employed for analyzing some mustards (Fisher, T. L., Jaskot, M. and Sass, S. Edgewood Arsenal Technical Report 4321, Trace Estimation and Differentiation of Some Mustards Employing Gas-Liquid Chromatography). However, aqueous samples cannot be analyzed directly by GC but must undergo a lengthy extraction and workup procedure before analysis can be performed.
High performance (pressure) liquid chromatography (HPLC) using a reverse phase column has achieved state-of-art analytical separation technology due to the development of improved columns and more sensitive detectors. The most commonly used sensitive detector is based on ultraviolet/visible absorption or fluorescence. However, sulfur mustards and their decomposition by-products do not absorb or fluoresce in this spectral region and hence as such are not amenable to HPLC analysis with a UV or fluorescent detector.